You can adapt this recipe to whatever greens you have: spinach, kale, collards, or beet greens, for example. Just adjust the boiling time (spinach takes seconds to cook; collards take several minutes), and make sure to transfer the boiled greens to ice water to stop the cooking and preserve the nutrients. The roasted onion and softened red pepper add a pleasing sweetness to the dish. On another evening, serve these savory greens as a sauce for spaghetti.